Letter to the EditorPolynuclear Aluminium and Acute Aluminium Toxicity in the Fish
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Aluminum polymers formed following alum treatment of lake water
2010, ChemosphereAlum (aluminum sulfate) is increasingly being used in lake management to control internal recycling of phosphorus from bottom sediments. Alum added to water undergoes rapid hydrolysis reactions, forming an amorphous Al(OH)3 floc with a high capacity for sorption of phosphorus. While it is known that the Al(OH)3 floc transforms over time to more ordered microcrystalline and crystalline gibbsite phases, there remains an incomplete understanding of the forms of Al present immediately following alum addition to lake water. A laboratory study was thus undertaken to evaluate the forms of Al present following alum addition using ferron (8-hydroxy-7-iodo-5-quinolinesulfonic acid) timed-colorimetric and 27Al-NMR measurements. A polymeric Al species with moderate reactivity with ferron (Alb2) was initially formed, although it rapidly transformed to a less ferron-reactive colloidal form (Alc) and also decomposed at low alum doses to monomeric Al (Ala) in response to pH increases associated with outgassing of CO2. The Ala fraction in these solutions could be adequately estimated based upon measured pH assuming Al solubility was controlled by an amorphous Al(OH)3 phase. Al13 was inferred from ferron measurements to be present, but only at quite low concentrations in the alum-treated waters.
Transformation of positively charged aluminium-species in unstable mixing zones following liming
2004, Science of the Total EnvironmentLiming is widely used to counteract chronic toxicity of positively charged monomeric aluminium species (Ali). Immediately after liming, unstable mixing zones are formed due to the sudden increase in pH. Transformation of monomeric Ali species takes place instantaneously and transient positively charged Al polymers, being acute toxic to fish, are formed in the mixing zones. Using in situ hollow fibre ultrafiltration interfaced with ion chromatography in unstable mixing zone field experiments performed in two river systems situated south and southwest of Norway, information on time-dependent transformations of low molecular mass (LMM) and high molecular mass (HMM) positively charged Ali-species has been followed. The formation of HMM Ali species from LMM Ali occurred rapidly following liming. HMM Ali species have a certain lifetime and are transformed to high molecular mass neutral Al-species (HMM Alo) and then to non-reactive colloidal Al species (HMM Alc). Concentration levels of transient Al-species formed in the mixing zone and the rate of transformation depend on the concentrations of LMM Ali species, Al complexing ligands (DOC and Si) in the input water and on pH in the mixing zone after liming. A dynamic model describing transformation processes influencing the Al speciation in mixing zones following a sudden increase in pH is suggested. Based on the experimental results, associated rate constants and half-lives for transient Al-species were estimated.
Aluminum forms in drinking water and risk of Alzheimer's disease
2000, Environmental ResearchThe objective of this study was to assess the relation between long-term exposure to different aluminum (Al) forms in drinking water and Alzheimer's disease (AD). The study participants were selected from a random sample of the elderly population (≥70 years of age) of the Saguenay-Lac-Saint-Jean region (Quebec). Sixty-eight cases of Alzheimer's disease diagnosed according to recognized criteria were paired for age (±2 years) and sex with nondemented controls. Aluminum speciation was assessed using established standard analytical protocols along with quality control procedures. Exposure to Al forms (total Al, total dissolved Al, monomeric organic Al, monomeric inorganic Al, polymeric Al, Al3+, AlOH, AlF, AlH3SiO2+4, AlSO4) in drinking water was estimated by juxtaposing the subject's residential history with the physicochemical data of the municipalities. The markers of long-term exposures (1945 to onset) to Al forms in drinking water were not significantly associated with AD. On the other hand, after adjustment for education level, presence of family cases, and ApoE ε4 allele, exposure to organic monomeric aluminum estimated at the onset of the disease was associated with AD (odds ratio 2.67; 95% CI 1.04–6.90). On average, the exposure estimated at the onset had been stable for 44 years. Our results confirm prime the importance of estimation of Al speciation and consideration of genetic characteristics in the assessment of the association between aluminum exposure and Alzheimer's disease.
Chemical speciation dynamics and toxicity assessment in aquatic systems
1998, Ecotoxicology and Environmental SafetyThe key to risk assessment of contaminant effects in the environment (water, sediments, soil) is the ability to document cause-and-effect relationships. In ecotoxicological research, biotic responses are related to quantified contaminant concentrations, which in most cases are still expressed in terms of “total elemental concentration” and not in terms of “elemental species.” However, it becomes evident that the abundance and distribution of pollutants in the environment, their bioavailability, and their toxicity to aquatic and terrestrial organisms (including humans) can often be better understood in terms of “elemental species.” The persistence, mobility, chemical reactivity, sorption dynamics, and so on of contaminants in soil and water are governed by a range of changing physicochemical parameters (pH, temperature, organic matter, suspended solids, etc.), which finally dictate the effects at the organism level. Examples are given to demonstrate that knowledge of the nature and concentration of elemental species of pollutants is crucial in assessing the impact of contaminants on aquatic ecosystems. The experimental approach to evaluate chemical speciation dynamics in relation to toxic effects is illustrated in a case study on the acute toxicity of aluminum in mixing zones at the confluence of rivers with different pH values. This study under nonequilibrium ecosystem conditions has provided new insights into the mechanism of toxicity of aluminum to freshwater organisms. In conclusion, an integrative approach by environmental chemists and ecotoxicologists is recommended to evaluate environmental pollution. Studies on the assessment of the impact of changing physicochemical parameters on the transformation kinetics and chemical speciation of pollutants, which finally determine toxicity and bioconcentration in organisms, deserve more attention in environmental toxicology.
Influence of aluminum on motility and swarming of Pseudomonas sp. and Arthrobacter sp.
1997, FEMS Microbiology LettersThe effect of Al on the motility and the swarming of Pseudomonas sp. and Arthrobacter sp. was investigated. pH calibration curves were determined in semi-solid agar which enabled us to distinguish between the effects of aluminum and protons. Motility of the bacteria was distinctly influenced by Al but this effect could be attributed to the increased acidity accompanying Al addition. The swarming of Pseudomonas sp. is reported for the first time. The swarming ability decreased with both Al and HCl addition to the medium but the obstruction due to aluminum was significantly stronger than the influence of HCl.
Kinetic constraints in acute aluminium toxicity in the rainbow trout (Ocorhynchus mykiss)
1996, Journal of Theoretical BiologyWe have designed a laboratory bioassay to expose fish to kinetically determined differences in aluminium hydroxide solution chemistry. We have used this system to demonstrate the hitherto unexpected result of an acute aluminium toxicity in the fish at a pH of 6.5. Supporting experiments have demonstrated that the mechanism of toxicity at this pH was probably an asphyxiation brought about by aluminium-induced changes in the rheological and diffusional properties of the mucus lining of the gill epithelium.